- Description
- The Go MCP SDK used Go's standard encoding/json.Unmarshal for JSON-RPC and MCP protocol message parsing in versions prior to 1.3.1. Go's standard library performs case-insensitive matching of JSON keys to struct field tags — a field tagged json:"method" would also match "Method", "METHOD", etc. This violated the JSON-RPC 2.0 specification, which defines exact field names. A malicious MCP peer may have been able to send protocol messages with non-standard field casing that the SDK would silently accept. This had the potential for bypassing intermediary inspection and coss-implementation inconsistency. Go's standard JSON unmarshaling was replaced with a case-sensitive decoder in commit 7b8d81c. Users are advised to update to v1.3.1 to resolve this issue.
- Source
- security-advisories@github.com
- NVD status
- Analyzed
- Products
- mcp_go_sdk
CVSS 4.0
- Type
- Secondary
- Base score
- 7
- Impact score
- -
- Exploitability score
- -
- Vector string
- CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Severity
- HIGH
CVSS 3.1
- Type
- Primary
- Base score
- 7.5
- Impact score
- 3.6
- Exploitability score
- 3.9
- Vector string
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- Severity
- HIGH
- security-advisories@github.com
- CWE-178
- Hype score
- Not currently trending
[
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:lfprojects:mcp_go_sdk:*:*:*:*:*:*:*:*",
"matchCriteriaId": "F490537C-6089-4989-A1B4-4072EADBA4DF",
"versionEndExcluding": "1.3.1",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
]